British police are trying to track down the suspected gang leaders who employed 19 mainly Chinese shellfish gathers who drowned in a bay in northwest England.

Although police believe they have recovered all of the bodies, a final search was made Saturday in Morecambe Bay, a treacherous stretch of water where the workers perished when they were engulfed by the incoming tide. They were gathering cockles, a local variety of shellfish.

The 310 square kilometer bay is notorious for its fast-rising tides and quicksand.

Sixteen in the work party did survive. Fourteen of them are of Chinese origin. Interpreters have been brought in to aid the inquiries.

Police are now looking for who employed these people. Lancashire Detective Superintendent Mick Bradwell says he expects arrests in the coming days.

"There has been a great response to the press appeals that have been made, and I have a large number of names of people who are gang masters, and we are now narrowing that list down as to the people who were involved in this particular incident," he said.

Although the immigration status of the workers is not fully known at the moment, Mr. Bradwell says it looks like a classic case of exploitation, with the workers being paid only one pound sterling, the equivalent of less than $2 a day.

"These are tragic events, and the fact that vulnerable people are being used to work in these circumstances, physically hard, for about one pound for a full nine-hour shift, I just think is appalling," said Superintendent Bradwell.

Assistant police chief Julia Hodson says the unfortunate case of the shellfish gatherers is just one example of labor exploitation in the area, tied in with organized crime engaged in smuggling illegal immigrants.

"We have recently profiled what that looks like in the northwest region," she said. "And the incidence of organized criminality around cockle [shellfish] picking is just one aspect of that. There are other aspects, as well."

The case has sparked widespread calls in Britain for laws to be tightened in the murky world of gang labor.